Hi!
Thanks for this project, I've just found it and I'm going to try it at home.
Zynaddsubfx has 3 synth engines, one of them is PADSynth, a very complex synth, and it can export to wav files, which can be used by SamplerBox !

If I need to apply reverb or chorus, I just have to use SOX to do batch processing of all the wav files, with one command line.